Pinch valve operated delivery devices of the above mentioned type are for example used in single-use liquid handling systems applied in the biotechnology or medical field. Single-use systems employ typically pre-sterilized components that are in fluid contact with the processing fluid. Such components are preferably made from incinerable plastics materials and are often disposed of after use to avoid cleaning prior to re-use and related cleaning validation. By having the disposable components pre-sterilized and clean-room manufactured, all cleaning and cleaning validation prior to processing is also eliminated. Sterilization methods are usually gamma irradiation, E-beam sterilization, autoclaving but other methods exist. Pinch valves are often used with such disposable single-use components due to the simple and cost-effective principle. In manufacturing of biopharmaceuticals for example, such single-use systems are adapted for liquid handling in filtration and chromatography, chromatography systems, such as the ÄKTA™ ready system from GE Healthcare, Sweden, for example.
Due to the design principle of pinch valves such devices suffer from dead volumes caused by minimum length of tubing required when pinch valves are arranged in fluid manifolds. This problem arises especially at systems used in production scale employing higher flow rates as this requires fluid lines of larger diameter and increased dimensions of tubing and components. Typically, tubing in production scale equipment has an inner diameter of ¼ ″(6.25 mm) or larger. With such larger diameter tubing, an increasing risk for convective mixing of fluid in manifolds exists. In FIG. 1, such a device is schematically shown having six fluid ducts A connected to a manifold B. A pump P sucks fluid from the manifold B. A pinch valve C is disposed in each of the fluid ducts A. In FIG. 1, if the outer pinch valve on the left side is opened, fluid from this opened fluid duct flows through the manifold B through the pump P and is delivered to the system. However, on its way to the pump P, the fluid from the opened fluid duct will also reach into the space d in the other fluid ducts between the manifold B and the respective closed pinch valve C. Due to these dead volumes the device cannot be rinsed effectively and there is a risk for contamination and carry over when running fractions and sequential protocols such as in chromatography. The objective of the present invention is to eliminate or at least greatly reduce said risk.